The first edition of this Manual, judged by its spread around the world, seems to have been useful to hospital bacteriologists. It was translated into Japanese by Dr Riichi Sakazaki, who will also translate this edition.

It has not been easy to prepare a worthy successor; not only have I been unable to discuss and argue every sentence with my colleague, but I have missed the ready access to libraries that one has when working in a large research institution. However, I have been greatly helped by the Librarians at Colindale (Miss B. H. Whyte) and the Royal Society of Medicine (Mr P. Wade) and their staffs.

In this edition Chapter 2 and Appendices A, B, C and E, originally written mainly by Dr Steel, are little changed; most of the other chapters have been completely rewritten. Chapters 8 and 9 are entirely new, as are Appendices D, F, G and H. I must thank Mr A. Waltho, of the Medical Research Council's Central Store, who gave me great help in preparing the list of firms which supply media and chemicals (Appendix H) and, together with Dr O. M. Lidwell, suggested and drafted what became Table 2.1.